1. Field
The present disclosure relates to micro-electromechanical systems (MEMS) and, in particular, to a method for integrating piezoelectric MEMS, such as PZT multimorph switches or bulk acoustic wave (BAW) resonators, with gallium nitride (GaN) technology and an apparatus integrating piezoelectric MEMS with GaN technology.
2. Related Art
The related art deals with the integration of PZT films with GaAs substrates, and the fabrication of PZT BAW devices on these substrates, as shown in “Lead Zirconate Titanate Thin Films for Microwave Device Applications”, S. Arscott, R. E. Miles, and S. J. Milne, Sol-Gel Materials for Device Applications, IEEE proc.-Circuits Devices Syst., Vol. 145, no. 5, October 1998.
A BAW device comprises a piezoelectric layer placed between two electrodes. When a radio frequency (RF) signal is applied across the device, a mechanical wave is produced in the piezoelectric layer. The thickness of the piezoelectric layer determines the resonant frequency, and the fundamental resonance occurs when the wavelength of the mechanical wave is about twice the thickness of the piezoelectric layer. As the thickness of the piezoelectric layer is reduced, the resonance frequency is increased.
The prior art does not explicitly address integration issues of PZT and GaAs MMIC technology.
The present disclosure presents a significant advantage over the related art because it considers PZT/GaN MMIC process integration, as GaN is the material of choice for high power applications.